SATURDAY UPDATE: Flight cancellations were on the rise Saturday thanks to a winter storm that was expected to drop snow along a 1,500-mile path stretching from Colorado to the Mid-Atlantic.Nearly 250 flights were canceled nationwide and another 400 delayed as of 10:45 a.m. ET, according to flight-tracking service FlightAware.com. Full update here: Snow! Airlines waive fees, cancellations extend into Sunday

Southwest, Delta, United and Frontier had all waived fees for travelers flying through certain airports in the storm’s path. Additional waivers were possible as the storm moved east, with forecasts calling for snow at major airports such as Denver, Indianapolis, Cincinnati and the Missouri airports of Kansas City and St. Louis.

By Sunday, accumulating snow was possible for Washington Dulles and Washington Reagan National, though current forecasts called for just 3 inches or less.

On Friday, about 215 flights had been canceled nationwide as of 2:05 p.m. ET, according to flight-tracking service FlightAware. Many of those were related to the storm, including in Missouri, where some flights were pre-emptively canceled ahead of the snow.

In St. Louis, about 70 combined arrivals and departures had been canceled by early Friday afternoon. A handful of flights were canceled elsewhere in the country because of the storm, dubbed Winter Storm Gia by The Weather Channel.

By Friday morning, United had rolled out two waivers. One covered its Denver hub and nine other airports in Colorado. The second covered a dozen airports in the Midwest and Ohio Valley, including Cincinnati, Indianapolis, Lexington and Louisville in Kentucky and Kansas City and St. Louis in Missouri, among others. The Colorado waiver covered Friday flights while the Midwest waiver was good for flights on both Friday and Saturday. The waivers generally allowed eligible flyers to make one change to their itineraries without paying the standard change fee of $200 or more.

Frontier’s policy was similar, covering its Friday flights at Denver and Colorado Springs.

Southwest is unique among U.S. airlines in that it doesn't charge change fees. Instead, its waivers allow travelers to make one change to their itineraries without paying a recalculated fare, which is standard practice at all U.S. carriers. Southwest’s rebooking policy covers Friday and Saturday flights at Denver; Kansas City; St. Louis; Omaha Nebraska; and Des Moines, Iowa. Saturday and Sunday flights at Cincinnati and Indianapolis. By Friday afternoon, Southwest's waiver had expanded to include Saturday and Sunday flights at eight additional airports (Baltimore/Washington; Charlotte, North Carolina; Greenville/Spartanburg, South Carolina; Louisville; Raleigh/Durham, North Carolina; Richmond, Virginia; Washington Dulles and Washington Reagan National).

Delta issued its waiver late Friday morning, offering a fee-free change for customers tickets to fly through Kansas City or St. Louis on Friday and Saturday.

A bulldozer drops a load of what used to be the center runway at Seattle-Tacoma International into a dump truck. The airport is in the process of repaving the 9,426-foot runway during a nearly six-month process. Jeremy Dwyer-Lindgren for USA TODAY

An American Airlines Airbus A321 passes by the now under-construction center runway at Seattle-Tacoma International on July 17, 2015. The runway, built in 1969, was torn up in order to be rebuilt. Jeremy Dwyer-Lindgren for USA TODAY